#40543 [Fbk]: pack/unpack bug
ID: 40543
Updated by: tony2001@php.net
Reported By: dedmajor at gmail dot com
Status: Feedback
Bug Type: Strings related
Operating System: linux x86_64
PHP Version: 5.2.1
New Comment:
Please try using this CVS snapshot:
http://snaps.php.net/php5.2-latest.tar.gz
For Windows:
http://snaps.php.net/win32/php5.2-win32-latest.zip
Previous Comments:
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[2007-04-23 17:19:13] petr dot stastny at centrum dot cz
Okay, I will say exactly where I have this problem:
PHP 5.2.1
# cat /proc/cpuinfo
processor : 0
vendor_id : AuthenticAMD
cpu family : 15
model : 67
model name : AMD Athlon(tm) 64 X2 Dual Core Processor 3800+
# uname -a
Linux silver 2.6.18-8.1.1.el5 #1 SMP Mon Apr 9 09:43:24 EDT 2007 x86_64
x86_64 x86_64 GNU/Linux
php -r 'print_r(unpack("N", pack("N", 41445)));
returns the same as metioned int the original message about this bug:
-2147442203
If you use sprintf('%b',....), you can see:
1111111111111111111111111111111110000000000000001010000111100101
First 32 bits are set to 1.
There is no problem on Intel Xeon 64-bit processor as I could test.
------------------------------------------------------------------------
[2007-04-23 09:18:20] tony2001@php.net
Not reproducible (both on 32bit and 64bit).
------------------------------------------------------------------------
[2007-04-22 18:44:55] petr dot stastny at centrum dot cz
Sorry, it is converted to SIGNED int
------------------------------------------------------------------------
[2007-04-22 18:43:53] petr dot stastny at centrum dot cz
The problem is that first 32 bits are set to 1 (not 0) in the output of
unpack() function, thus it is interpreted as very large number and then
converted to unsigned int for PHP representation.
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[2007-04-12 20:11:55] wez@php.net
This isn't bogus, this is a real bug that causes pain.
N is there for people writing code that talks to network services that
need to convert numbers from network byte order to the native format.
Also note that we get a bonus crash bug on 64-bit platforms too:
$fail = '\x00\x00\x00\x8c';
$result = unpack('Nsize', $fail);
$size = $result['size'] & 0xffffffff; // BANG!
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Thread (10 messages)